Improvement in spirit-levels



A. F. HYDE.

Spirit Level-s.

N.0.]54,677. I Patnted Sept.1,18-74.

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g I I ITNESSES. Alt/( ,16.

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UNITED STATES PATE1\TT OFFIoE.

ALBE F. HYDE, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN SPIRIT-LEVELS.

Specification forming part of Letters Patent No. 154,677, datedSeptember 1, 1874; application filed July 14, 1874.

' .of a spirit-level containing my improvements.

In these drawings, A represents a castmetal upright frame of a size andform adapted v to receive the level and plumb glasses of the instrument,the former being shown at B, and the latter at O, as disposedimmediately under it. To the under side of the central glasssupport A, Iattach, by means of screws, rivets, or in any suitable manner, a,

flat steel plate, I), which is the base or table of the level, and iscomposed, preferably, of steel, and the under side of this plate is tobe planed to a true and straight surface. I furthermore truss the frameA and table I) by suitable chords or braces a wand b b, and posts 0 c,substantially as shown in the drawings, by which means the entirelevel-frame is rendered vvery strong, stiff, and light.

Heretofore' the frames of spirit-levels have been composed of a solidbar of wood or castiron, in the former instance being comparativelyfrail and destructible, and liable to twist and change by changes oftemperature and age, while the cast-iron frames are 'very heavy andunwieldy, and are easily broken.

A level constructed as herein explained possesses, among others, thefollowing advantages: First, I am enabled to employ a much longer plumbglass than is possible in a wooden beam level, thus producing a moreperfect instrument 5 second, when once properly adjusted it will remaintrue and correct for any length of time, as its adjustment is unaffectedby moisture or variations of temperature; third, it is not liable tobecome scarred orfractured, as in the case of a wooden frame, or crackedor broken like one of castiron, and it is in fact, with reasonable care,indestructible; fourth, it is very light and convenient to use, isornamental in appearance, and its plumb-glass is more exposed, andconsequently more easily read, than in levels heretofore made.

I claim A spirit-level frame composed of a central glass-support, a baseor table, and a truss frame or braces, substantially as and for purposesstated.

, ALBE F. HYDE.

Witnesses:

FRANCIS E. FAXON, W. E. BOARDMAN.

